PURPOSE: To facilitate operation of a printer, by starting paper feeding by opening a bail shaft after a predetermined lapse of time from the detection of the insertion of a cut sheet when a sheet feeder is used, and enabling printing by reclosing the bail shaft when a printing starting position is reached.

CONSTITUTION: In the case of using cut paper, when the leading end of the paper 4 inserted reaches a PE sensor 1, a detection signal S2 from a PE- detecting circuit B2 is turned ON. When signals S1, S2 are detected, a condition- discriminating circuit B3 starts a timer waiting circuit B4 to generate a waiting time signal of a predetermined time length. At the end of the waiting time signal, the circuit B3 turns ON a bail shaft opening/closing control signal S3, and a bail shaft opening/closing controlling circuit B5 opens a bail shaft 2. When a signal 5 indicative of completion of paper feeding is received by the circuit B3, the circuit B3 turns OFF the bail shaft opening/closing signal S3, and the circuit B5 closes the bail shaft 2. Therefore, the paper 4 is set into a printable condition on a platen 3.